/*
 * EAP server/peer: EAP-SAKE shared routines
 * Copyright (c) 2006-2007, Jouni Malinen <j@w1.fi>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * Alternatively, this software may be distributed under the terms of BSD
 * license.
 *
 * See README and COPYING for more details.
 */

#include "includes.h"

#include "common.h"
#include "sha1.h"
#include "wpabuf.h"
#include "eap_defs.h"
#include "eap_sake_common.h"


static int eap_sake_parse_add_attr(struct eap_sake_parse_attr *attr,
                                   const u8 *pos)
{
        size_t i;

        switch (pos[0]) {
        case EAP_SAKE_AT_RAND_S:
                wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_RAND_S");
                if (pos[1] != 2 + EAP_SAKE_RAND_LEN) {
                        wpa_printf(MSG_DEBUG, "EAP-SAKE: AT_RAND_S with "
                                   "invalid length %d", pos[1]);
                        return -1;
                }
                attr->rand_s = pos + 2;
                break;
        case EAP_SAKE_AT_RAND_P:
                wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_RAND_P");
                if (pos[1] != 2 + EAP_SAKE_RAND_LEN) {
                        wpa_printf(MSG_DEBUG, "EAP-SAKE: AT_RAND_P with "
                                   "invalid length %d", pos[1]);
                        return -1;
                }
                attr->rand_p = pos + 2;
                break;
        case EAP_SAKE_AT_MIC_S:
                wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_MIC_S");
                if (pos[1] != 2 + EAP_SAKE_MIC_LEN) {
                        wpa_printf(MSG_DEBUG, "EAP-SAKE: AT_MIC_S with "
                                   "invalid length %d", pos[1]);
                        return -1;
                }
                attr->mic_s = pos + 2;
                break;
        case EAP_SAKE_AT_MIC_P:
                wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_MIC_P");
                if (pos[1] != 2 + EAP_SAKE_MIC_LEN) {
                        wpa_printf(MSG_DEBUG, "EAP-SAKE: AT_MIC_P with "
                                   "invalid length %d", pos[1]);
                        return -1;
                }
                attr->mic_p = pos + 2;
                break;
        case EAP_SAKE_AT_SERVERID:
                wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_SERVERID");
                attr->serverid = pos + 2;
                attr->serverid_len = pos[1] - 2;
                break;
        case EAP_SAKE_AT_PEERID:
                wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_PEERID");
                attr->peerid = pos + 2;
                attr->peerid_len = pos[1] - 2;
                break;
        case EAP_SAKE_AT_SPI_S:
                wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_SPI_S");
                attr->spi_s = pos + 2;
                attr->spi_s_len = pos[1] - 2;
                break;
        case EAP_SAKE_AT_SPI_P:
                wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_SPI_P");
                attr->spi_p = pos + 2;
                attr->spi_p_len = pos[1] - 2;
                break;
        case EAP_SAKE_AT_ANY_ID_REQ:
                wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_ANY_ID_REQ");
                if (pos[1] != 4) {
                        wpa_printf(MSG_DEBUG, "EAP-SAKE: Invalid AT_ANY_ID_REQ"
                                   " length %d", pos[1]);
                        return -1;
                }
                attr->any_id_req = pos + 2;
                break;
        case EAP_SAKE_AT_PERM_ID_REQ:
                wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_PERM_ID_REQ");
                if (pos[1] != 4) {
                        wpa_printf(MSG_DEBUG, "EAP-SAKE: Invalid "
                                   "AT_PERM_ID_REQ length %d", pos[1]);
                        return -1;
                }
                attr->perm_id_req = pos + 2;
                break;
        case EAP_SAKE_AT_ENCR_DATA:
                wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_ENCR_DATA");
                attr->encr_data = pos + 2;
                attr->encr_data_len = pos[1] - 2;
                break;
        case EAP_SAKE_AT_IV:
                wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_IV");
                attr->iv = pos + 2;
                attr->iv_len = pos[1] - 2;
                break;
        case EAP_SAKE_AT_PADDING:
                wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_PADDING");
                for (i = 2; i < pos[1]; i++) {
                        if (pos[i]) {
                                wpa_printf(MSG_DEBUG, "EAP-SAKE: AT_PADDING "
                                           "with non-zero pad byte");
                                return -1;
                        }
                }
                break;
        case EAP_SAKE_AT_NEXT_TMPID:
                wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_NEXT_TMPID");
                attr->next_tmpid = pos + 2;
                attr->next_tmpid_len = pos[1] - 2;
                break;
        case EAP_SAKE_AT_MSK_LIFE:
                wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_IV");
                if (pos[1] != 6) {
                        wpa_printf(MSG_DEBUG, "EAP-SAKE: Invalid "
                                   "AT_MSK_LIFE length %d", pos[1]);
                        return -1;
                }
                attr->msk_life = pos + 2;
                break;
        default:
                if (pos[0] < 128) {
                        wpa_printf(MSG_DEBUG, "EAP-SAKE: Unknown non-skippable"
                                   " attribute %d", pos[0]);
                        return -1;
                }
                wpa_printf(MSG_DEBUG, "EAP-SAKE: Ignoring unknown skippable "
                           "attribute %d", pos[0]);
                break;
        }

        if (attr->iv && !attr->encr_data) {
                wpa_printf(MSG_DEBUG, "EAP-SAKE: AT_IV included without "
                           "AT_ENCR_DATA");
                return -1;
        }

        return 0;
}


/**
 * eap_sake_parse_attributes - Parse EAP-SAKE attributes
 * @buf: Packet payload (starting with the first attribute)
 * @len: Payload length
 * @attr: Structure to be filled with found attributes
 * Returns: 0 on success or -1 on failure
 */
int eap_sake_parse_attributes(const u8 *buf, size_t len,
                              struct eap_sake_parse_attr *attr)
{
        const u8 *pos = buf, *end = buf + len;

        os_memset(attr, 0, sizeof(*attr));
        while (pos < end) {
                if (end - pos < 2) {
                        wpa_printf(MSG_DEBUG, "EAP-SAKE: Too short attribute");
                        return -1;
                }

                if (pos[1] < 2) {
                        wpa_printf(MSG_DEBUG, "EAP-SAKE: Invalid attribute "
                                   "length (%d)", pos[1]);
                        return -1;
                }

                if (pos + pos[1] > end) {
                        wpa_printf(MSG_DEBUG, "EAP-SAKE: Attribute underflow");
                        return -1;
                }

                if (eap_sake_parse_add_attr(attr, pos))
                        return -1;

                pos += pos[1];
        }

        return 0;
}


/**
 * eap_sake_kdf - EAP-SAKE Key Derivation Function (KDF)
 * @key: Key for KDF
 * @key_len: Length of the key in bytes
 * @label: A unique label for each purpose of the KDF
 * @data: Extra data (start) to bind into the key
 * @data_len: Length of the data
 * @data2: Extra data (end) to bind into the key
 * @data2_len: Length of the data2
 * @buf: Buffer for the generated pseudo-random key
 * @buf_len: Number of bytes of key to generate
 *
 * This function is used to derive new, cryptographically separate keys from a
 * given key (e.g., SMS). This is identical to the PRF used in IEEE 802.11i.
 */
static void eap_sake_kdf(const u8 *key, size_t key_len, const char *label,
                         const u8 *data, size_t data_len,
                         const u8 *data2, size_t data2_len,
                         u8 *buf, size_t buf_len)
{
        u8 counter = 0;
        size_t pos, plen;
        u8 hash[SHA1_MAC_LEN];
        size_t label_len = os_strlen(label) + 1;
        const unsigned char *addr[4];
        size_t len[4];

        addr[0] = (u8 *) label; /* Label | Y */
        len[0] = label_len;
        addr[1] = data; /* Msg[start] */
        len[1] = data_len;
        addr[2] = data2; /* Msg[end] */
        len[2] = data2_len;
        addr[3] = &counter; /* Length */
        len[3] = 1;

        pos = 0;
        while (pos < buf_len) {
                plen = buf_len - pos;
                if (plen >= SHA1_MAC_LEN) {
                        hmac_sha1_vector(key, key_len, 4, addr, len,
                                         &buf[pos]);
                        pos += SHA1_MAC_LEN;
                } else {
                        hmac_sha1_vector(key, key_len, 4, addr, len,
                                         hash);
                        os_memcpy(&buf[pos], hash, plen);
                        break;
                }
                counter++;
        }
}


/**
 * eap_sake_derive_keys - Derive EAP-SAKE keys
 * @root_secret_a: 16-byte Root-Secret-A
 * @root_secret_b: 16-byte Root-Secret-B
 * @rand_s: 16-byte RAND_S
 * @rand_p: 16-byte RAND_P
 * @tek: Buffer for Temporary EAK Keys (TEK-Auth[16] | TEK-Cipher[16])
 * @msk: Buffer for 64-byte MSK
 * @emsk: Buffer for 64-byte EMSK
 *
 * This function derives EAP-SAKE keys as defined in RFC 4763, section 3.2.6.
 */
void eap_sake_derive_keys(const u8 *root_secret_a, const u8 *root_secret_b,
                          const u8 *rand_s, const u8 *rand_p, u8 *tek, u8 *msk,
                          u8 *emsk)
{
        u8 sms_a[EAP_SAKE_SMS_LEN];
        u8 sms_b[EAP_SAKE_SMS_LEN];
        u8 key_buf[EAP_MSK_LEN + EAP_EMSK_LEN];

        wpa_printf(MSG_DEBUG, "EAP-SAKE: Deriving keys");

        wpa_hexdump_key(MSG_DEBUG, "EAP-SAKE: Root-Secret-A",
                        root_secret_a, EAP_SAKE_ROOT_SECRET_LEN);
        eap_sake_kdf(root_secret_a, EAP_SAKE_ROOT_SECRET_LEN,
                     "SAKE Master Secret A",
                     rand_p, EAP_SAKE_RAND_LEN, rand_s, EAP_SAKE_RAND_LEN,
                     sms_a, EAP_SAKE_SMS_LEN);
        wpa_hexdump_key(MSG_DEBUG, "EAP-SAKE: SMS-A", sms_a, EAP_SAKE_SMS_LEN);
        eap_sake_kdf(sms_a, EAP_SAKE_SMS_LEN, "Transient EAP Key",
                     rand_s, EAP_SAKE_RAND_LEN, rand_p, EAP_SAKE_RAND_LEN,
                     tek, EAP_SAKE_TEK_LEN);
        wpa_hexdump_key(MSG_DEBUG, "EAP-SAKE: TEK-Auth",
                        tek, EAP_SAKE_TEK_AUTH_LEN);
        wpa_hexdump_key(MSG_DEBUG, "EAP-SAKE: TEK-Cipher",
                        tek + EAP_SAKE_TEK_AUTH_LEN, EAP_SAKE_TEK_CIPHER_LEN);

        wpa_hexdump_key(MSG_DEBUG, "EAP-SAKE: Root-Secret-B",
                        root_secret_b, EAP_SAKE_ROOT_SECRET_LEN);
        eap_sake_kdf(root_secret_b, EAP_SAKE_ROOT_SECRET_LEN,
                     "SAKE Master Secret B",
                     rand_p, EAP_SAKE_RAND_LEN, rand_s, EAP_SAKE_RAND_LEN,
                     sms_b, EAP_SAKE_SMS_LEN);
        wpa_hexdump_key(MSG_DEBUG, "EAP-SAKE: SMS-B", sms_b, EAP_SAKE_SMS_LEN);
        eap_sake_kdf(sms_b, EAP_SAKE_SMS_LEN, "Master Session Key",
                     rand_s, EAP_SAKE_RAND_LEN, rand_p, EAP_SAKE_RAND_LEN,
                     key_buf, sizeof(key_buf));
        os_memcpy(msk, key_buf, EAP_MSK_LEN);
        os_memcpy(emsk, key_buf + EAP_MSK_LEN, EAP_EMSK_LEN);
        wpa_hexdump_key(MSG_DEBUG, "EAP-SAKE: MSK", msk, EAP_MSK_LEN);
        wpa_hexdump_key(MSG_DEBUG, "EAP-SAKE: EMSK", emsk, EAP_EMSK_LEN);
}


/**
 * eap_sake_compute_mic - Compute EAP-SAKE MIC for an EAP packet
 * @tek_auth: 16-byte TEK-Auth
 * @rand_s: 16-byte RAND_S
 * @rand_p: 16-byte RAND_P
 * @serverid: SERVERID
 * @serverid_len: SERVERID length
 * @peerid: PEERID
 * @peerid_len: PEERID length
 * @peer: MIC calculation for 0 = Server, 1 = Peer message
 * @eap: EAP packet
 * @eap_len: EAP packet length
 * @mic_pos: MIC position in the EAP packet (must be [eap .. eap + eap_len])
 * @mic: Buffer for the computed 16-byte MIC
 */
int eap_sake_compute_mic(const u8 *tek_auth,
                         const u8 *rand_s, const u8 *rand_p,
                         const u8 *serverid, size_t serverid_len,
                         const u8 *peerid, size_t peerid_len,
                         int peer, const u8 *eap, size_t eap_len,
                         const u8 *mic_pos, u8 *mic)
{
        u8 _rand[2 * EAP_SAKE_RAND_LEN];
        u8 *tmp, *pos;
        size_t tmplen;

        tmplen = serverid_len + 1 + peerid_len + 1 + eap_len;
        tmp = os_malloc(tmplen);
        if (tmp == NULL)
                return -1;
        pos = tmp;
        if (peer) {
                if (peerid) {
                        os_memcpy(pos, peerid, peerid_len);
                        pos += peerid_len;
                }
                *pos++ = 0x00;
                if (serverid) {
                        os_memcpy(pos, serverid, serverid_len);
                        pos += serverid_len;
                }
                *pos++ = 0x00;

                os_memcpy(_rand, rand_s, EAP_SAKE_RAND_LEN);
                os_memcpy(_rand + EAP_SAKE_RAND_LEN, rand_p,
                          EAP_SAKE_RAND_LEN);
        } else {
                if (serverid) {
                        os_memcpy(pos, serverid, serverid_len);
                        pos += serverid_len;
                }
                *pos++ = 0x00;
                if (peerid) {
                        os_memcpy(pos, peerid, peerid_len);
                        pos += peerid_len;
                }
                *pos++ = 0x00;

                os_memcpy(_rand, rand_p, EAP_SAKE_RAND_LEN);
                os_memcpy(_rand + EAP_SAKE_RAND_LEN, rand_s,
                          EAP_SAKE_RAND_LEN);
        }

        os_memcpy(pos, eap, eap_len);
        os_memset(pos + (mic_pos - eap), 0, EAP_SAKE_MIC_LEN);

        eap_sake_kdf(tek_auth, EAP_SAKE_TEK_AUTH_LEN,
                     peer ? "Peer MIC" : "Server MIC",
                     _rand, 2 * EAP_SAKE_RAND_LEN, tmp, tmplen,
                     mic, EAP_SAKE_MIC_LEN);

        os_free(tmp);

        return 0;
}


void eap_sake_add_attr(struct wpabuf *buf, u8 type, const u8 *data,
                       size_t len)
{
        wpabuf_put_u8(buf, type);
        wpabuf_put_u8(buf, 2 + len); /* Length; including attr header */
        if (data)
                wpabuf_put_data(buf, data, len);
        else
                os_memset(wpabuf_put(buf, len), 0, len);
}
